Lithography Technique Research Articles

Superexchange coupling of donor qubits in silicon

Atomic engineering in a solid-state material has the potential to functionalize the host with novel phenomena. STM-based lithographic techniques have enabled the placement of individual phosphorus atoms at selective lattice sites of silicon with atomic precision. Here we show that by placing four phosphorus donors spaced 10–15 nm apart from their neighbors in a linear chain, one can realize coherent spin coupling between the end dopants of the chain, analogous to the superexchange interaction in magnetic materials. Since phosphorus atoms are a promising building block of a silicon quantum computer, this enables spin coupling between their bound electrons beyond nearest neighbors, allowing the qubits to be separated by 30–45 nm. The added flexibility in architecture brought about by this long-range coupling not only reduces gate densities but can also reduce correlated noise between qubits from local noise sources that are detrimental to error-correction codes. We base our calculations on a full-configuration-interaction technique in the atomistic tight-binding basis, solving the four-electron problem exactly, over a domain of a million silicon atoms. Our calculations show that superexchange can be tuned electrically through gate voltages where it is less sensitive to charge noise and donor-placement errors. Published by the American Physical Society 2024

Fabrication of a Low Cost Superhydrophobic Substrate for Surface Enhanced Laser-Induced Breakdown Spectroscopy and Its Utility through Identification of Electrolyte Variation for Oral Cancer Detection.

Ultratrace elemental detections from a limited volume of samples can offer significant benefits in biomedical fields. However, it can be challenging to concentrate the particles being analyzed in a small area to improve the accuracy of detection. Ring-like deposits on the edges of colloidal droplets are a vexing problem in many applications. Herein, we report ultratrace elemental detection using a superhydrophobic surface-enhanced laser-induced breakdown spectroscopy (SELIBS) substrate fabricated by laser ablation followed by a soft lithography technique. In this work, the SELIBS spectra on a superhydrophobic polydimethylsiloxane (PDMS) substrate replicated from a laser-patterned master Teflon substrate are investigated. This work highlights the application of this newly created superhydrophobic substrate for detecting trace elements in body fluids using SELIBS. The developed PDMS substrate was successfully adopted to investigate the electrolyte variation in serum samples of oral cancer patients and normal volunteers. Principal component analysis (PCA) and match-no-match analysis were used to distinguish the elemental variation in cancer and control groups.

Self-Aligning Nanojunctions for Integrated Single-Molecule Circuits.

Robust, high-yield integration of nanoscale components such as graphene nanoribbons, nanoparticles, or single-molecules with conventional electronic circuits has proven to be challenging. This difficulty arises because the contacts to these nanoscale devices must be precisely fabricated with angstrom-level resolution to make reliable connections, and at manufacturing scales this cannot be achieved with even the highest-resolution lithographic tools. Here we introduce an approach that circumvents this issue by precisely creating nanometer-scale gaps between metallic carbon electrodes by using a self-aligning, solution-phase process, which allows facile integration with conventional electronic systems with yields approaching 50%. The electrode separation is controlled by covalently binding metallic single-walled carbon nanotube (mCNT) electrodes to individual DNA duplexes to create mCNT-DNA-mCNT nanojunctions, where the gap is precisely matched to the DNA length. These junctions are then integrated with top-down lithographic techniques to create single-molecule circuits that have electronic properties dominated by the DNA in the junction, have reproducible conductance values with low dispersion, and are stable and robust enough to be utilized as active, high-specificity electronic biosensors for dynamic single-molecule detection of specific oligonucleotides, such as those related to the SARS-CoV-2 genome. This scalable approach for high-yield integration of nanometer-scale devices will enable opportunities for manufacturing of hybrid electronic systems for a wide range of applications.

A self-training end-to-end mask optimization framework based on semantic segmentation network

As the process advances and the minimum linewidth gets closer to the physical limit, inverse lithography technique (ILT) is widely used for optical proximity correction (OPC). However, the computational overhead of the ILT method is high, and the printability of the mask is poor. In response to these limitations, we proposed ERFNet-ILT, a self-training method for an end-to-end learning framework for generating optimized masks directly from layout patterns, which introduces a feature fusion module at the end of the encoder and uses dilated convolution to expand the receptive field, thereby extracting layout pattern information such as edges, vertices and corners of the layout pattern from the feature map. The framework has shorter model building time and higher mask printability. Compared with the state-of-the-art methods, experimental quantitative results show that the proposed framework achieves 2.5 % squared L2 error and 7.9 % process variation band reduction within a comparable mask correction time.

Patterned ZnO nanorods/indium sulfide based self-powered photoelectrochemical photodetectors

The present work reports the excellent alignment of zinc oxide nanorod arrays (ZnO NRAs) patterned via the maskless lithography technique which was used as a photoanode material for photoelectrochemical (PEC) photodetection applications. The effects of circular patterns having different diameters, different gaps between circles, and the utilization of indium sulfide (In2S3) as a light-absorbing material in the visible region have been investigated in the PEC photodetector (PD) system in two different electrolytes. PEC PD performance evaluation confirmed the positive effect of patterned ZnO NRAs-based photoanode in the presence of In2S3, enhancing 982.9 μAcm−2 of current density (Jphoto), 54.6 mA/W of responsivity (Rs), 1.98 × 1011 Jones of detectivity (D*) and 8.18 × 104 of selectivity (S%) values. Besides, the best-performing patterned ZnO NRAs/In2S3 has been used to construct a quasi-solid state assembly using the prepared ionic-gel electrolyte and consequently, 2.19 × 1011 Jones of D* value has been observed. After all, the proposed PEC PD devices exhibited fast rise/decay times(τr/τd) in millisecond extent at 400 nm of wavelength.

High-fidelity source mask optimization for suppressing line-end shortening.

Source mask optimization (SMO) is a widely used computational lithography technique for compensating lithographic distortion. However, line-end shortening is still a key factor that cannot be easily corrected and affects the image fidelity of lithography at advanced nodes. This paper proposes a source mask optimization method that suppresses line-end shortening and improves lithography fidelity. An adaptive hybrid weight method is employed to increase the weights of the line end during the optimization, which adaptively updates the weights in each iteration according to the edge placement error (EPE). A cost function containing a penalty term based on the normalized image log slope (NILS) is established to ensure the fidelity of the overall feature when paying more attention to the line-end region. The scope of this penalty term is regulated by widening and extending the split contour to further reduce the line-end shortening. Simulation results show that the proposed method can effectively suppress the line-end shortening and improve the lithography fidelity compared with the traditional SMO method.

Tunable Periodic Nanopillar Array for MAPbI3 Perovskite Photodetectors with Improved Light Absorption.

In the field of optoelectronic applications, the vigorous development of organic-inorganic hybrid perovskite materials, such as methylammonium lead triiodide (MAPbI3), has spurred continuous research on methods to enhance the photodetection performance. Periodic nanoarrays can effectively improve the light absorption of perovskite thin films. However, there are still challenges in fabricating tunable periodic patterned and large-area perovskite nanoarrays. In this study, we present a cost-effective and facile approach utilizing nanosphere lithography and dry etching techniques to create a large-area Si nanopillar array, which is employed for patterning MAPbI3 thin films. The scanning electron microscopy (SEM) and X-ray diffraction (XRD) results reveal that the introduction of nanopillar structures did not have a significant adverse effect on the crystallinity of the MAPbI3 thin film. Light absorption tests and optical simulations indicate that the nanopillar array enhances the light intensity within the perovskite films, leading to photodetectors with a responsivity of 11.2 A/W and a detectivity of 7.3 × 1010 Jones at 450 nm in wavelength. Compared with photodetectors without nanostructures, these photodetectors exhibit better visible light absorption. Finally, we demonstrate the application of these photodetector arrays in a prototype image sensor.

Au nanopillar array prepared by selective etching of Au-Sr3Al2O6 vertically aligned nanocomposite thin films

Au nanostructures offer a wide range of applications such as surface-enhanced Raman spectroscopy, photovoltaics, and biosensors. Effective integrating well-controlled Au nanostructures on chip via a self-assembly process remains challenging as most of the Au nanostructures were prepared by either chemical synthesis methods or lithography patterning techniques. This study introduces a simple two-step approach for fabricating Au nanostructures on substrate with well controlled morphology and density. First, epitaxial Au-Sr3Al2O6 (SAO) vertically aligned nanocomposites (VANs) were deposited on SrTiO3 substrates. Second, by subsequently dissolving the water-soluble SAO matrix, various Au nanostructures ranging from 0D nanoparticles to 1D nanopillars are demonstrated. The Au morphology tuning is achieved by varying the deposition parameters of the VANs. This method eliminates the need of harsh chemical solutions and tedious lithography/patterning steps. These findings provide a novel strategy for tailoring the Au nanostructures and their optical properties, and, demonstrating on-chip integration for advanced optical device applications.

Origami nanogap electrodes for reversible nanoparticle trapping.

We present a facile desktop fabrication method for origami-based nanogap indium tin oxide (ITO) electrokinetic particle traps, providing a simplified approach compared to traditional lithographic techniques and effective trapping of nanoparticles. Our approach involves bending ITO thin films on optically transparent polyethylene terephthalate (PET), creating an array of parallel nanogaps. By strategically introducing weak points through cut-sharp edges, we successfully controlled the spread of nanocracks. A single crack spanning the constriction width and splitting the conductive layers forms a nanogap that can effectively trap small nanoparticles after applying an alternating electric potential across the nanogap. We analyze the conditions for reversible trapping and optimal performance of the nanogap ITO electrodes with optical microscopy and electrokinetic impedance spectroscopy. Our findings highlight the potential of this facile fabrication method for the use of ITO at active electro-actuated traps in microfluidic systems.

Bolometric IR photoresponse based on a 3D micro-nano integrated CNT architecture.

A new 3D micro-nano integrated M-shaped carbon nanotube (CNT) architecture was designed and fabricated. It is based on vertically aligned carbon nanotube arrays composed of low-density, mainly double-walled CNTs with simple lateral external contacts to the surroundings. Standard optical lithography techniques were used to locally tailor the width of the vertical block structure. The complete sensor system, based on a broadband blackbody absorber region and a high-resistance thermistor region, can be fabricated in a single chemical vapor deposition process step. The thermistor resistance is mainly determined by the high junction resistances of the adjacent aligned CNTs. This configuration also provides low lateral thermal conductivity and a high temperature coefficient of resistance (TCR). These properties are advantageous for new bolometric sensors with high voltage responsivity and broadband absorption from the infrared (IR) to the terahertz spectrum. Preliminary performance evaluations have shown current and voltage responsivities of 2 mA/W and 30 V/W, respectively, in response to IR (980 nm) absorption for a 20 × 20 μm2 device. The device exhibits an exceptionally fast response time of ≈0.15 ms, coupled with a TCR of -0.91 %/K. These attributes underscore its high operating speed and responsivity, respectively. In particular, the device maintains excellent thermal stability and reliable operation at elevated temperatures in excess of 200 °C, extending its potential utility in challenging environmental conditions. This design allows for further device miniaturization using optical lithography techniques. Its unique properties for mass production through large-scale integration techniques make it important for real-time broadband imaging systems.

Kinetic Monte Carlo simulation of selective area growth of mix deposited organic molecules

The selective area growth approach (namely the self-assembly of molecules on pre-patterned surfaces) that takes into account the properties of organic molecular materials and traditional lithography techniques, is expected to play a significant role in manufacturing organic micro-nano patterns for photoelectric and full-color display. The manufacture of organic devices with tunable multicolor patterned films depends on the control of nucleation distribution of two or more organic molecules by using a selective area growth approach, particularly through the application of mixed deposition growth that can enhance the nucleation efficiency of multicolor thin films. However, till now the issue of mixed deposition growth of two kinds of organic molecules has been rarely reported, owing to the complexity in experimental operation. In this work, the selective area growth of mixed deposition of two kinds of molecules is studied by molecular kinetic Monte Carlo approach in order to find the experimental conditions for separating two kinds of molecular growth. In the simulation, the interaction energy between the two molecules is adjusted and controlled to study its influence on the separately selective area growth of the two molecules. The results show that when the intermolecular interaction energy is weak, the planar molecules and the non-planar molecules exhibit completely different growth behaviors. The most of non-planar molecules gather at the top of the electrode in an island mode, while planar molecules mainly accumulate in a layer-by-layer mode on the sides of the electrode. On the contrary, when the intermolecular interaction energy is strong, the number of non-planar particles on the tops decreases and a large number of planar particles appear. Moreover, on the sides of the electrode, the doping nucleation of planar molecules and non-planar molecules also exists, resulting in the failure of molecular phase separation growth. It proves that the intermolecular interaction energy can affect separately area-selective growth of various organic molecules. Therefore, when several different kinds of molecules are mixed and deposited, relatively pure crystalline monochromatic films can be obtained at the top and on the sides of the electrode, respectively, by appropriately adjusting the intermolecular interaction energy, which can further facilitate the application of multi-color organic micro-nano pattern in display and other fields.

RuleLearner: OPC Rule Extraction From Inverse Lithography Technique Engine

RuleLearner: OPC Rule Extraction From Inverse Lithography Technique Engine

A sensorised, microfluidic Ussing chamber manufactured by stereolithography and soft lithography techniques

Motivated by the need for improved platforms in biomedical research, this study addresses challenges associated with traditional Ussing chamber systems, widely used in studying biological barriers like the epithelial barrier of the gut. These challenges include complexity, high sample volumes, and limited compatibility. By combining stereolithography and soft lithography techniques, a microfluidic Ussing chamber is manufactured, overcoming these limitations, and incorporating compatibility with microscopy. Validation through Trans-Epithelial Electrical Resistance (TEER) measurements confirms its efficacy in assessing ion permeability dynamics, utilizing Caco-2 cell monolayers. The study showcases the capability of the manufactured chamber for sensing impact of calcium on tight junctions.

Electron beam lithography of GeTe through polymorphic phase transformation.

We report two previously undiscovered phases of GeTe including the sphalerite (c-) phase and the hexagonal (h-) phase with interlayer van der Waals gaps. A polymorphic phase transformation from rhombohedral α-GeTe to c- and h-GeTe at near room temperature is first realized via electron beam irradiation. Their underlying thermodynamics and kinetics are illustrated using the in situ heating experiments and molecular dynamics simulations. Density-functional theory calculations indicate that c-GeTe exhibits typical metallic behavior and h-GeTe is a narrow-gap semiconductor with a strong spin-orbital coupling effect. Our findings shed light on a strategy for designing GeTe-based quantum devices compromising nanopillars and heterostructures via an atomic-scale electron beam lithography technique.

Extreme ultraviolet lithography reaches 5 nm resolution.

Extreme ultraviolet (EUV) lithography is the leading lithography technique in CMOS mass production, moving towards the sub-10 nm half-pitch (HP) regime with the ongoing development of the next generation high numerical aperture (high NA) EUV scanners. Hitherto, EUV interference lithography (EUV-IL) utilizing transmission gratings has been a powerful patterning tool for the early development of EUV resists and related processes, playing a key role in exploring and pushing the boundaries of photon-based lithography. However, achieving patterning with HPs well below 10 nm using this method presents significant challenges. In response, this study introduces a novel EUV-IL setup that employs mirror-based technology and circumvents the limitations of diffraction efficiency towards the diffraction limit that is inherent in conventional grating-based approaches. The results are line/space patterning of the HSQ resist down to HP 5 nm using the standard EUV wavelength 13.5 nm, and the compatibility of the tool with shorter wavelengths beyond EUV. Mirror-based interference lithography paves the way towards the ultimate photon-based resolution at EUV wavelengths and beyond. This advancement is vital for scientific and industrial research, addressing the increasingly challenging needs of nanoscience and technology and future technology nodes of CMOS manufacturing in the few-nanometer HP regime.

Inherently Selective Atomic Layer Deposition for Optical and Sensor Applications: Microreactor Direct Atomic Layer Processing (μDALP™)

In parallel to additive manufacturing leading the revolution in traditional manufacturing, the same principles can revolutionize traditional thin film deposition techniques. Where lithography and vapor phase deposition techniques struggle, for example, with rapid iterations for prototyping or incompatibility with the used chemistry, additive manufacturing can shine. Indeed, several approaches are in development for 3D nanopriting1,2,3.Atomic Layer Deposition, and in more general Atomic Layer Processing, offers a unique opportunity for localized 3D processing/printing due to its two-step process. While simple in theory, due to well-developed examples of Spatial Atomic Layer Deposition (SALD), in practice miniturization of SALD requires substantial effort into the creation of suitable micro-nozzles. Uniquely, ATLANT 3D has developed proprietary Spatial ALD micronozzles, naming the process microreactor Direct Atomic Layer Processing - µDALPTM.The µDALPTM process undergoes the same cyclic ALD process but, thanks to the in-house microreactor development, is only done in a localized area. The microreactor or micronozzle confines the flows of gases used for ALD within a µm-scale area on the substrate, wherein the reactive species adsorb on the surface to deposit one monolayer of the desired material. Similarly, to spatial ALD, the creation of this monolayer then hinges on the movement of the substrate.4 Since the µDALPTM process is based on physical separation, it is theoretically compatible with any ALD process. As such, the material capabilities can match traditional ALD and exceed other special or patterning thin film techniques, such as lithography, which can be costly and time-consuming, especially for rapid prototyping required for innovation.Films deposited with ATLANT 3D technology have been shown to produce high-quality, crystalline, atomically precise thin films.1 It has been used to fabricate temperature (Fig.1) and capacitive sensors with sensitivities that meet or exceed those of devices made using conventional vapor phase deposition techniques.5 Low-cost rapid prototyping facilitated by ATLANT 3D technology of such devices enables design innovation and optimization not possible with other thin film deposition techniques.ATLANT 3D platform provides flexibility in deposition geometry (Fig.2) that enables a range of optical applications that require high-precision fabrication techniques. Optically transparent films can be used as localized thin protective layers for device encapsulation, as well as for atomic corrections of defects. Alternating deposition materials enable multilayer mirror fabrication of custom dimensions. Smooth thickness gradients can be used to manufacture ultrathin optical lenses. Overlapping depositions with discrete steps enable the manufacturing of binary lenses and phase masks. Growth rate enhancement in rastered direct processing mode using ATLANT 3D technology can produce periodic grating structures.1 Conformal coatings on complex surfaces can act as functionalization layers or seed layers for further material deposition through e.g. electrochemical processes.[1] Kundrata I. et al., ALD/ALE 2022 [Int. Conf.], 2022 [2] de la Huerta C. A. M. et al., arXiv, 2020, 0523. [3] Winkler, R. et al., J. Appl. Phys., 2019, 125, 210901[4] Paul Poodt., JVSTA., 2012, 30, 010802[5] Kundrata, I. et al., Small Methods., 2022, 6 (5), 2101546 Figure 1

Zero-Gap Porous Silicon Membrane Electrodes for Alkaline Electrolysis

Despite only accounting for a fraction of the annual global hydrogen production, commercial application of water electrolysis is expected to grow significantly in line with global climate action goals1. Furthermore, water electrolysis driven by renewable energy is expected to aid in nullifying the intermittency of renewable energy sources such as wind and solar photovoltaics2.Two main types of water electrolysis have found widespread commercial application – alkaline water electrolysis (AWEs) and polymer electrolyte membrane electrolysis (PEMEs). While PEMEs operate at higher current densities and higher efficiencies, they require expensive precious metal catalysts such as Ir-based cathodes and Pt-based anodes3. In addition, PEMEs generally have a shorter lifespan than AWEs4. Therefore, AWEs are better suited for gigawatt-scale deployment5. Furthermore, it has been shown that AWEs with Ni-based catalysts can compete with Ir and Pt-based PEMEs if a dramatic reduction in the thickness of the separator can be achieved6.A key development in AWEs is the adoption of a zero-gap electrode (ZGE) configuration in which the electrodes are pressed directly on the surface of the separator. It is possible to leverage silicon-based lithographic techniques to produce separators with well-defined pore sizes and porosities, which are significantly thinner than commercially available AWE separators. This has been previously demonstrated for photoelectrochemical devices7. Such porous silicon devices typically suffer from the high gas crossover. One method to limit gas crossover is infilling the pores with ionomers. However, due to volumetric expansion in electrolytes, ionomers – such as the commonly used PEME membrane material, Nafion – are not suitable for microfabricated devices8.In this work, we report the fabrication of stable porous silicon separators with metal electrodes in a zero-gap configuration. These porous silicon separators exhibit ionic resistance comparable to Zirfon (the most commonly used AWE separator9) but at an order of magnitude lower porosity. The ordered and well-defined pore structure of the microfabricated separators allows us to study the influence of separator properties such as pore size and porosity on ionic conductivity and gas crossover in cylindrical pores with no interconnections. References International Energy Agency, The Future of Hydrogen, IEA, IEA, Paris, (2021), p. 203 https://www.iea.org/reports/hydrogen.L. M. Pierpoint, Energy Policy, 96, 751–757 (2016).A. S. Gago et al., ECS Trans., 85, 3 (2018).M. David, C. Ocampo-Martínez, and R. Sánchez-Peña, Journal of Energy Storage, 23, 392–403 (2019).M. Schalenbach, Aleksandar R. Zeradjanin, Olga Kasian, Serhiy Cherevko, and Karl J.J. Mayrhofer, Int. J. Electrochem. Sci., 1173–1226 (2018).M. Schalenbach et al., J. Electrochem. Soc., 163, F3197 (2016).W. J. C. Vijselaar et al., Advanced Energy Materials, 9, 1803548 (2019).T. Pichonat and B. Gauthier-Manuel, Fuel Cells, 6, 323–325 (2006).R. Phillips and C. W. Dunnill, RSC Adv., 6, 100643–100651 (2016).

Miniature Fuel Cell with Monolithically Fabricated Si Electrodes- Application of a PDMS Flow Channel for Operando Observation -

Miniature fuel cells have attracted attention as an ultimate portable power source, and we have developed monolithically fabricated Si electrodes for the miniature fuel cells [1,2]. In the fuel cells, two Si electrodes with porous Pt catalyst layer are pressed onto either side of a PEM (polymer electrolyte membrane) , and the prototype fuel cells showed promising performances of over 500mW/cm2 output at 313K with H2-O2. However, the high output was obtained with only small reaction area. Along with enhancement of the reaction area, the performance dropped. We assumed that the performance drop is caused by flooding due to increased water production, which was ignored because MEMS fuel cells are dimensionally small and the outputs are also small. In this study, we attempted to observe the behavior of produced water on the fuel flow channel using a novel transparent channel cover as shown in figure 1. Furthermore, it was assumed that the produced water stays in the concave portions on the catalyst layer, and stripe-shaped projections were formed on the channel cover to prompt drainage of the produced water from the fuel channels.The transparent fuel channel cover was fabricated with PDMS using soft lithography techniques. Initially, a mold for the cover was made with a dry film resist. Micro stripe pattern with 40μm width were made. Considering the PDMS shrinkage during polymerization, the mold pattern had to be formed a few percent larger than the desired shape. Figure 2 shows the whole view of the PDMS channel cover on a miniature fuel cell with Si electrodes. The reaction on the Si substrate was 1mm and 4mm long. Within the area, 100μm x 100μm sections were etched down to the backside catalyst layer. Magnified view on the reaction area is shown in figure 3. It was found that the stripes were finely aligned on the concave portions on the Si electrode.Figure 4 shows the polarization curves of the power generation tests. Results with the novel fuel channel cover with stripes showed higher output compared to the conventional simple cuboid straight shape cover. Figure 5 shows the microscopic view of the channel. While produce water droplets were observed on downstream area in the conventional cuboid shape channel, no droplets were observed with the novel channel cover. It was assumed that drainage of the produced water was successfully prompted and smooth fuel supply to the catalyst layer was realized by the novel fuel channel cover. Acknowledgement This work was partly performed under the Cooperative Research Program of “NJRC Mater. &Dev.” References [1] M. Kobayashi, T. Suzuki, M. Hayase, Journal of Power Sources, 267, 622-628 (2014).[2] R. Shirai, et al., Journal of The Electrochemical Society, 166(15), D834 (2019) Figure 1

Understanding Growth Mechanism of Atomic Layer Deposition of Tisiox for Spacer in Double Patterning Process

The aggressive scaling down of patterning technology in semiconductor industry is challenging owing to the limitation of current extreme ultraviolet EUV lithography technique, thus applying self-aligned double patterning (SADP) is essential. In this regard, TiSiOx may be a promising spacer material for SADP, which is beneficial to tolerate high aspect ratio structure triggered by shrinkage in patterning size. However, atomic layer deposition (ALD) of quaternary materials is usually faced to unexpected growth characteristics leading to undesired film qualities, while precise control of thickness and film properties is vital to achieve SADP. This work provide understanding of how growth characteristics of ALD TiSiOx are deviated according to process temperature. At 100 °C, hygroscopic TiSiOx surface which is originated by the presence of Ti-O-Si bond is exposed to H2O by-product leading to enhanced growth rate of TiSiOx compared to ideal case. If the process temperature is increased to 200 °C, opposite behavior is observed since hygroscopic TiSiOx surface characteristic is no more dominant to growth rate of ALD TiSiOx due to dehydroxylation. Theses nonconventional growth characteristics dramatically influence on hydroxyl concentration in TiSiOx films resulting in different spacer qualities such as dry etch rate and elastic modulus. These correlative results suggest that the process conditions should be modulated to suppress hydroxyls incorporation into growing TiSiOx surface during ALD to obtain a high-quality TiSiOx thin films for SADP.

Sensitivity in nanomechanical pedestal MEMS cantilever

Nanomechanical resonator-based sensing devices are used in medical diagnostics based on their high-frequency dynamic behavior. Cantilevers fall into the category of Nanomechanical resonators. It also resembles a resonator whose shape is like that of a nanowire clamped at one end. As the surface-to-volume ratio of a nanowire resonator increases due to scaling down, surface stress plays a crucial role in the mechanical behavior of a resonator. Piezoresistive MEMS cantilevers are used for vapor phase analysis of volatile compounds and gas. Studies were done to address the mass sensitivity issues and fractures associated with bioceramic and nanocomposite coatings-based cantilever resonators. The studies show how the sensing performance can be determined or tuned. Finite Element modelling of a pedestal cantilever resonator was done which takes into consideration the mass sensitivity issues associated with linear cantilevers. MEMS cantilever structures were fabricated using lithographic techniques. SiCN, a suitable material for MEMS in harsh operating conditions were deposited on Silicon substrates showing high hardness (20 GPa) and modulus (220 GPa). The electrical conduction taking place between the nanoindentation tip and sample was explored. The surface stress of 711 MPa was determined based on pedestal cantilever deflections, Fracture taking place on the sample surface was found to affect the conduction and tip displacements in AFM nanoindentations. The sharpness of the tip was found to have an influence on the tip-sample conduction mechanism useful for MEMS applications. The sensitivity associated with cell mass detection was reported to get affected by film deposition stress and formation of surface cracks and puts a challenge for doing future work.